Sudden, Chronic Low pH: A Theory...

[Dom]

Maintaining a healthy pH range isn't something that is usually a problem for me. I find that weekly water changes with Instant Ocean Reef Crystals keeps me at 8.2... usually.

Over the last 4 to 6 weeks, I've struggled to keep my pH up around the 8.2 range and find that it drops as low as 7.6. I do not like this!

I began dosing buffer and have been able to maintain the 8.2 for the short term, but it bugs me that what was never a problem has suddenly become one. Something has changed!

If I understand correctly (please let me know if I say something incorrect or inaccurate), your tank is in equilibrium with the room air. This means that O2 and CO2 levels in the tank will roughly match that of the room in which the tank resides.

I've purchased and calibrated a Pinpoint pH monitor for a real time display of my pH.

What has worked to correct the problem has been an open window in the room where the tank resides and a strong fan pointed at the ceiling for circulation. But still; this isn't something that has been necessary until the beginning of May. What's changed?

I have a theory:

I have about 5 Ficus trees that I keep in the living room with the tank during the winter months plus a host of other plants. In the spring, I place all of these plants outside on my deck. As I understand plants, they consume CO2 during the day and produce O2. At night, they do the opposite.

Is it possible that the room CO2 has elevated as a result of removing the CO2 consuming plants from the room? If this is true, and the tank is in equilibrium where CO2 is concerned, then CO2 in the tank would elevate, driving down the pH.

Reasonable?

 

[Cory]

It's reasonable. I kind of doubt those plants could remove that much co2, but youll never know unless you test it. Try putting them inside and see what happens to the ph.

 

[Lasse]

Your outside CO2 should bee around 400 ppm - it correspond to a pH in saltwater around 8.15 - 8.20 (equilibrium). Has your aquarium temperature rise also? - Higher temperature - more bacteria activity - more CO2 production in the tank. Yes - the removing of the plants can affect the content of CO2 in your living room. Try to measure CO2 in the room and near the air intake of the skimmer to be sure.

Sincerely Lasse

 

[rock_lobster]

Check your tank flow and surface agitation.. Try increasing if that doesnt work I would be surprised assuming your alkalinity isnt below 6. I once thought this was my problem living in a small condo with no circulation but after boosting my flow up with a lot of surface agitation, my pH has been in a much better range. Went from 7.7-8 and now it is at 8-8.4 after adding a good wavemaker.

 

[Randy Holmes-Farley]

I do not believe the plants can be helping very much, unless it is packed with plants like a greenhouse.

Think of it this way:

Take all of the food you eat yourself and your family and the food you feed to tank, dogs, etc., (not to mention gas stoves) It all ends up as CO2. For plants to take up that amount of CO2, they would have to grow in mass similar to the mass of food consumed. Very few people have enough daily increase in plant mass to match the CO2 produced.

 

[beaslbob]

I think balancing your tank with macro and other algae (or at least adding more) will result is a Ph of 8.2 just before lights out.

Regardless of the ambient conditions.

What can (and will) happen the tank becomes a net consume of co2 and supplier of oxygen each 24 hour period.

my .02

 

[JohnnyRambo]

Try running an air stone just underneath your pumps to help circulate some micro bubbles. This should help with the co2 in the tank. It even helps with coral growth as well! I do this every night and stop it in the day. Your ph usually drops when lights are off but not by much

 

[Dom]

Try running an air stone just underneath your pumps to help circulate some micro bubbles. This should help with the co2 in the tank. It even helps with coral growth as well! I do this every night and stop it in the day. Your ph usually drops when lights are off but not by much

Lights on: 8.2
Lights off: 8.1

I have a wood stone in the sump. I've placed it by the intake of the protein skimmer. This serves to increase the micro bubbles AND oxygenate.

 

[JohnnyRambo]

Lights on: 8.2
Lights off: 8.1

I have a wood stone in the sump. I've placed it by the intake of the protein skimmer. This serves to increase the micro bubbles AND oxygenate.

It doesn't compare to your display tank. You protein skimmer is much smaller volume than your tank, obviously. It doesn't have that much effect. If you have your protein skimmer running along with micro bubbles in your tank it helps a lot more. Even having a reverse cycle on a refugium helps out with ph.

 

[rock_lobster]

I bet if you just point one of your power heads to the surface your pH will magically be perfect:)

 

[rock_lobster]

I do not believe the plants can be helping very much, unless it is packed with plants like a greenhouse.

Think of it this way:

Take all of the food you eat yourself and your family and the food you feed to tank, dogs, etc., (not to mention gas stoves) It all ends up as CO2. For plants to take up that amount of CO2, they would have to grow in mass similar to the mass of food consumed. Very few people have enough daily increase in plant mass to match the CO2 produced.

I remember trying to calculate this for my tank. Dont remember exactly but it would take somewhere around 40 full grown pine trees to remove all of the CO2 produced by day produced by me alone not to mention my girlfriend. my 600 squarefoot condo unfortunately couldnt hold a forest of pine trees.

 

[rock_lobster]

The surface of your tank water should be very turbulent then it will equilibrate fast. Putting micro bubbles in it or trying to oxygenate isnt going to do much of anything.

 

[Randy Holmes-Farley]

Try running an air stone just underneath your pumps to help circulate some micro bubbles. This should help with the co2 in the tank. It even helps with coral growth as well! I do this every night and stop it in the day. Your ph usually drops when lights are off but not by much

It only helps if the tank has less CO2 than the air. If not, it can make it worse.

 

[Randy Holmes-Farley]

The surface of your tank water should be very turbulent then it will equilibrate fast. Putting micro bubbles in it or trying to oxygenate isnt going to do much of anything.

As I mentioned above, aeration, even if perfect, often does not help a low pH problem if there is excessive CO2 in the air. :)

 

[Lasse]

As Randy point out - the carbon dioxide content of the ait coming in contact with your water will decide which pH your water will have in the long run. For most system – the skimmer has the highest contact area (interface) between water and air. Therefore – the carbon dioxide content in the incoming air to the skimmer can be the most important factor. Most of us has the skimmer in the cabinet and if the cabinet not is well aerated – the carbon dioxide content in the cabinet can be fairly high. One friend of mine had a carbon dioxide content in the room between 400 and 600 ppm – but in the cabinet – the concentration was over 1000 ppm. The equilibrium pH of 1000 ppm CO2 in the air is around 8 and for 400 ppm CO2 – around 8.15.

In Sweden cities (outside air CO2 around 400 - 450 ppm) the carbon dioxide concentration in a flat with two persons normally reach the 600 ppm level during winter time. We have a cold climate and well isolated houses. Therefore rather many persons has start to use CO2 scrubbers for the intake air to the skimmer – especially if they run Kalk reactors. This normally make a rise of the pH in the 0.1 – 0.15 range – more if there is large skimmer and if it is outside air in use.

In your case – the first I should do is to measure the carbon dioxide content in your room and cabinet. There is tables showing the equilibrium point according to the CO2 content of the air

With this information – it easier to make a decision what to do.

@Randy Holmes-Farley - Do you have any links to tables showing the equilibrium point - I can´t find any just now


Sincerely Lasse

 

[brandon429]

considering the threads that show all hobby kits read pH differently it only seems accurate anyone making ph decisions off hobby test kits should be work at min with a three different test average accepted number, and then it's still a toss up. That's my takeaway from reading google returns about hobby reef test kit variation testing

It isn't critical to react and respond to nitrate misreading, comparatively. If someone is off ten ppm in the too-clean mode, their bleaching (bioindicator) reflects mismeasure and they either verify or feed more and guide back. Ph is unforgiving

With ph we take the most precise reading in reefing+ read a color chart under varying conditions and fully plan around a number direct search returns show to vary. there is often no tank loss motivating the ph change reaction prep, or any chemical changes measured from sustained 50 orders too low claimed pH

Our ph readings in posts are under procedural scrutiny from meniscus consistency and basic lab technique which varies
Eyesight variances
Lighting variances for the reading s
Reagent shaking/prep for measure variance

All these and more are implicated in error reading threads. I say prove Co2 is immediately not the cause, bubble test, and if not then quit testing for ph by storing no detritus in the system (keep exported) and instead do magnesium calcium and alk detailing. Use bioindicators much or more than test kits truly I believe bioindicators are reaction filters.

Your reading may indeed be right but we never consider the alternative


my main question for Randy is how impactful is it to not approach all ph threads as reading in question mode i had to challenge my takeaway from reading those comparisons articles.

 

[Lasse]

I´m sorry - I´m was not clear enough. All of my discussion is based on the fact that an electronical pH device is in use. If the pH reading is based on a colour chart – do not do anything – you can´t rely on them as brandon429 states. Even if you have an electronical device – the most important is to look at the changes – not the absolute reading.

Sincerely Lasse